Torsion beam optimization design method and vehicle

Abstract

The present invention relates to the field of automobile manufacturing technology, and discloses a torsion beam optimization design method and a vehicle, comprising the following steps: constructing a response surface model based on the change and response relationship between multiple design variables of the crossbeam of the torsion beam and multiple design indicators; using a genetic algorithm to find the optimal solution of multiple design variables based on the response surface model and multiple design indicators; reconstructing a torsion beam finite element model based on the optimal solution, and verifying multiple design indicators of the reconstructed torsion beam finite element model. The beneficial effects brought about by the technical solution provided by the present invention include: constructing a response surface model based on the change and response relationship between multiple design variables of the crossbeam of the torsion beam and multiple design indicators, and using a genetic algorithm to find the optimal solution of multiple design variables, thereby obtaining the optimal design scheme of the torsion beam, so that the torsion beam can take into account all design indicators, reducing the design difficulty of the torsion beam, and accelerating the design speed.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile manufacturing, and in particular to a torsion beam optimization design method and a vehicle. Background Art

[0002] The torsion beam is an important component of the automobile chassis. As the carrier of the key components of the rear suspension, the torsion beam is particularly important for the safety and stability of the vehicle during driving. The torsion beam structure is a rigid structure connected by two longitudinal arms (the wheel center is located behind the bushing) through a crossbeam. This type of suspension relies on the elastic deformation of the crossbeam's own structure to control the suspension characteristics of the entire vehicle, ensure the vehicle's driving smoothness and maneuverability, and is an important safety component of the chassis. Therefore, the crossbeam of the torsion beam is the most critical sub-component. It connects the left and right wheel edges and has an important impact on the performance of various indicators. Designing the crossbeam well means designing the torsion beam well. Among them, there are multiple design indicators / performance targets for the torsion beam, including strength, torsional stiffness, modal frequency, weight, etc. There are also multiple design parameters / design variables for the crossbeam, including width, height, and plate thickness. Taking torsional stiffness as an example, torsional stiffness directly affects the comfort and handling of the vehicle. For conventional torsion beams, an increase in torsional stiffness means an increase in weight. However, reducing weight and maintaining appropriate torsional stiffness face the problem of stress concentration and insufficient strength of the torsion beam. Therefore, how to obtain the design variables that meet the requirements based on the required multiple design indicators is the difficulty of torsion beam design. Summary of the invention

[0003] The purpose of the present invention is to provide a torsion beam optimization design method and a vehicle, by constructing the change and response relationship between the design variables and the design indicators, solving the design variables that meet the requirements, so that the torsion beam takes into account all the design indicators and obtains the optimal design scheme.

[0004] In a first aspect, a torsion beam optimization design method proposed by the present invention comprises the following steps:

[0005] A response surface model is constructed based on the change and response relationship between multiple design variables and multiple design indicators of the torsion beam;

[0006] Based on the response surface model and the multiple design indicators, using a genetic algorithm to find the optimal solution of the multiple design variables;

[0007] The torsion beam finite element model is reconstructed based on the optimal solution, and multiple design indicators of the reconstructed torsion beam finite element model are verified.

[0008] Furthermore, there are three design variables, including width, height and plate thickness of the beam; there are six design indicators, including strength, torsional stiffness, shear center height, first-order bending modal frequency, first-order torsional modal frequency and weight.

[0009] Furthermore, the step of constructing a response surface model comprises:

[0010] Construct a finite element model of the torsion beam;

[0011] Conduct DOE orthogonal test analysis on design variables and design indicators to obtain the main effect relationship between design variables and design indicators;

[0012] The design variables and design indicators are fitted and the response surface model is constructed.

[0013] Furthermore, after constructing the finite element model of the torsion beam, the method also includes using the Morph method to establish a parametric variable model to change the width and height of the beam, and changing the thickness of the beam by changing the thickness attribute of the beam grid in the finite element model.

[0014] Furthermore, the step of performing DOE orthogonal test analysis to obtain the main effect relationship between the design variables and the design indicators includes: sampling the design variables using the full factor method, calculating the design indicators under each group of design variables, and performing DOE orthogonal test analysis on the data to obtain the contribution of the design variables to the design indicators.

[0015] Furthermore, the step of fitting the design variables and the design indicators includes:

[0016] The least squares method, sliding least squares method, Kriging method and radial basis function model are used to fit the three design variables and six design indicators in turn until the mean square error between the calculated fitting results and the simulation results of the finite element model is greater than 0.95.

[0017] Furthermore, the steps of verifying the strength of the reconstructed torsion beam finite element model include:

[0018] Based on the reconstructed torsion beam finite element model, a strength simulation condition is established, and the maximum stress value of the reconstructed torsion beam finite element model is simulated and calculated.

[0019] Furthermore, the steps of verifying the weight of the reconstructed torsion beam finite element model include:

[0020] The weight of the torsion beam was calculated by measuring the weight of the reconstructed finite element model of the torsion beam.

[0021] Furthermore, the steps of verifying the torsional stiffness of the reconstructed torsion beam finite element model include:

[0022] Based on the reconstructed finite element model of the torsion beam, a torsional stiffness simulation is established to obtain the wheel center displacement of the left and right wheels at both ends of the torsion beam. Based on the wheel center displacement and the torsion beam wheelbase, the torsional stiffness is calculated.

[0023] Furthermore, the steps of verifying the first-order bending modal frequency and the first-order torsional modal frequency of the reconstructed torsion beam finite element model include:

[0024] The free modal frequency analysis was performed on the reconstructed torsion beam finite element model, and the modal frequencies of each order were calculated. The first-order bending modal frequency and the first-order torsional modal frequency were identified through the modal vibration cloud diagram.

[0025] In a second aspect, the present invention further proposes a vehicle, comprising a torsion beam, wherein the width, height and thickness of the crossbeam of the torsion beam are determined by the torsion beam optimization design method in any of the above technical solutions.

[0026] The beneficial effects brought about by the technical solution provided by the present invention include: constructing a response surface model based on the change and response relationship between multiple design variables of the crossbeam of the torsion beam and multiple design indicators, and using a genetic algorithm to find the optimal solution of multiple design variables, thereby obtaining the optimal design solution of the torsion beam, so that the torsion beam can take into account all design indicators and reduce the design difficulty of the torsion beam. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 It is a schematic flow chart of the torsion beam optimization design method of the present invention.

[0029] Figure 2 It is a structural schematic diagram of the finite element model of the torsion beam in the torsion beam optimization design method of the present invention.

[0030] Figure 3 It is a schematic structural diagram of the crossbeam of the torsion beam of the present invention.

[0031] Figure 4 The present invention establishes a parameterized variable model of the beam using the Morph method.

[0032] Figure 5 for Figure 3 Schematic diagram of CC structure.

[0033] Figure 6It is a structural schematic diagram of the shear center position calculation of the beam of the present invention.

[0034] In the picture: 100- beam. DETAILED DESCRIPTION

[0035] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0036] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0037] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] Torsion beams involve multiple vehicle-level performance dimensions, such as reliability and durability, driving control and comfort, NVH, weight, etc. The performance of each dimension is decomposed into six design indicators for torsion beams, usually including strength, torsional stiffness, shear center height, first-order bending modal frequency, first-order torsional modal frequency, and weight.

[0039] The torsion beam is mainly welded by the crossbeam and the longitudinal arm, and the spring, shock absorber and wheel hub are installed on the corresponding supports. The crossbeam of the torsion beam is the most critical sub-component, which connects the left and right wheel edges and has an important impact on the performance of various indicators. Designing the crossbeam well means designing the torsion beam well.

[0040] There are multiple design indicators / performance targets for torsion beams, including strength, torsional stiffness, modal frequency, weight, etc. There are also multiple design parameters / design variables for the crossbeam, including width, height, and plate thickness. Taking torsional stiffness as an example, torsional stiffness directly affects the comfort and handling of the vehicle. For conventional torsion beams, an increase in torsional stiffness means an increase in weight. However, reducing weight and maintaining appropriate torsional stiffness face the problems of stress concentration and insufficient strength of the torsion beam. Therefore, how to derive design variables that meet the requirements based on the required multiple design indicators is a difficult point in torsion beam design.

[0041] This embodiment takes a U-shaped beam as an example. In the design of the beam, there are three important design variables, including the width, height and thickness of the beam. Correspondingly, there are six design indicators of the beam, including strength, torsional stiffness, shear center height, first-order bending modal frequency, first-order torsional modal frequency and weight.

[0042] Among them, strength refers to one of the mechanical properties that indicates the resistance of engineering materials (i.e. beams) to fracture and excessive deformation. Stiffness refers to the ability of a material or structure to resist elastic deformation when subjected to force. Torsional stiffness refers to the ability of a beam to resist elastic deformation when it is twisted. The shear center refers to the intersection of the two corresponding shear lines of action on the cross section when the beam is bent in two centroid principal inertia planes (planes formed by the centroid principal axes of each section). Both the first-order bending mode and the first-order torsional mode are low-order modes, which are generally the overall deformation of components. Here it refers to the overall deformation of the torsion beam. When the modal frequencies of the components are close, resonance often occurs, affecting the ride comfort of the vehicle. Therefore, the modal frequencies need to be designed so that the components avoid each other to avoid vehicle resonance.

[0043] like Figure 1 As shown, the torsion beam optimization design method proposed in the present invention includes the following steps: constructing a response surface model based on the change and response relationship between multiple design variables and multiple design indicators of the crossbeam of the torsion beam. Based on the response surface model and the multiple design indicators, using a genetic algorithm to find the optimal solution of the multiple design variables. Reconstructing the torsion beam finite element model based on the optimal solution, and verifying the multiple design indicators of the reconstructed torsion beam finite element model.

[0044] Wherein, based on the change and response relationship between multiple design variables and multiple design indicators of the crossbeam of the torsion beam, the steps of constructing the response surface model include:

[0045] Construct a finite element model of the torsion beam. Figure 2 As shown, the constructed torsion beam model or the finite element model of the torsion beam assembly is shown.

[0046] Figure 4The figure shows the parametric variable model of the beam established using the Morph method. Figure 3 , Figure 5 The width and height of the beam are changed by changing the thickness attribute of the beam grid in the finite element model to change the plate thickness of the beam.

[0047] The DOE orthogonal test analysis is performed on the design variables and design indicators to obtain the main effect relationship between the design variables and the design indicators. Among them, the design indicators are the final results or goals that need to be examined in the torsion beam design.

[0048] That is, the design variables are sampled using the full factor method, the design indicators under each group of design variables are calculated, and the data are analyzed by DOE orthogonal test to obtain the contribution of the design variables to the design indicators. Factors or factors refer to factors that may have an impact on the indicators and are compared under clear conditions in the experiment.

[0049] The so-called orthogonal experimental design is a scientific method that uses mathematical statistics and the principle of orthogonality to select an appropriate number of representative experimental points from a large number of experimental points and use the orthogonal table to reasonably arrange the experiment.

[0050] The sample size is usually 10 times the number of variables. The number of variables in this embodiment includes 3 design variables and 6 design indicators, so there are 9 variables in total, so the sample size is 90 groups. By performing DOE analysis on 90 groups of data, the main effect relationship between the variables can be obtained, that is, the contribution of the width, height and thickness of the beam to the strength, torsional stiffness, shear center height, first-order bending modal frequency, first-order torsional modal frequency and weight of the torsion beam assembly can be determined.

[0051] The design variables and design indicators are fitted and the response surface model is constructed.

[0052] That is, based on 90 sets of data, the least squares method (LSR), sliding least squares method (MLSM), Kriging method (HK) and radial basis function (RBF) model are used to fit the three design variables and six design indicators in turn until the mean square error of the calculated fitting result and the simulation result of the finite element model meets the requirements, that is, the goodness of fit R 2 Value>0.9.

[0053] Based on the response surface model and the multiple design indicators, a genetic algorithm (MOGA) is used to find the optimal solution of the multiple design variables, that is, to find the beam width, height and plate thickness values ​​under the minimum weight.

[0054] Among them, MOGA (Multi objective Genetic Algorithm) is also called multi-objective genetic algorithm.

[0055] Among them, the genetic algorithm (GA) is a computational model of biological evolution that simulates the natural selection and genetic mechanism of Darwin's theory of biological evolution, and searches for the optimal solution by simulating the natural evolution process. The algorithm uses mathematical methods and computer simulation operations to convert the problem-solving process into a process similar to the crossover and mutation of chromosome genes in biological evolution. When solving more complex combinatorial optimization problems, it can usually obtain better optimization results faster than some conventional optimization algorithms.

[0056] MOGA was proposed by Carlos M. Fonseca and Peter J. Fleming in 1993. MOGA adopts a fitness assignment mechanism based on ranking numbers and an adaptive fitness sharing strategy.

[0057] The torsion beam finite element model is reconstructed based on the optimal solution, and multiple design indicators of the reconstructed torsion beam finite element model are verified.

[0058] The optimal solution beam width, height and plate thickness values ​​are rounded to obtain an engineering design solution. A torsion beam model under this design variable is constructed, and six design indicators including strength, torsional stiffness, shear center height, first-order bending modal frequency, first-order torsional modal frequency and weight are verified and calculated.

[0059] The steps to verify the strength of the reconstructed torsion beam finite element model include:

[0060] Based on the reconstructed torsion beam finite element model, a strength simulation condition is established, and the maximum stress value of the reconstructed torsion beam finite element model is simulated and calculated.

[0061] The steps to verify the weight of the reconstructed torsion beam finite element model include:

[0062] The weight of the torsion beam was calculated by measuring the weight of the reconstructed finite element model of the torsion beam.

[0063] The steps to verify the torsional stiffness of the reconstructed torsion beam finite element model include:

[0064] Based on the reconstructed finite element model of the torsion beam, a torsional stiffness simulation is established to obtain the wheel center displacement of the left and right wheels at both ends of the torsion beam. Based on the wheel center displacement and the torsion beam wheelbase, the torsional stiffness is calculated.

[0065] For example, constrain the translation of the front hinge point of the finite element model in the X, Y, and Z directions, apply Z-direction forces F in opposite directions to the left and right wheel centers, and simulate the wheel center displacement D. Based on the wheel center displacement and the torsion beam track L, the torsional stiffness K is calculated. The specific calculation formula is:

[0066] K=F / tan -1 (2D / L)

[0067] The steps for verifying the first-order bending modal frequency and the first-order torsional modal frequency of the reconstructed torsion beam finite element model include:

[0068] The free modal frequency analysis was performed on the reconstructed torsion beam finite element model, and the modal frequencies of each order were calculated. The first-order bending modal frequency and the first-order torsional modal frequency were identified through the modal vibration cloud diagram.

[0069] like Figure 6 As shown, the shear center position (or shear center height e) of the cross section of the U-shaped beam can be approximately calculated using the following calculation formula for the shear center of the groove section:

[0070]

[0071] Where S is the shear center position, t f ,t w is the plate thickness, b is the height of the U-section, h is the width of the U-section, and e is the height from the shear center to the top of the U-section.

[0072] The present invention constructs a response surface model based on the change and response relationship between three design variables and six design indicators of the crossbeam of the torsion beam, and uses a genetic algorithm to find the optimal solution of multiple design variables, thereby obtaining the optimal design scheme of the torsion beam, so that the torsion beam can take into account all design indicators and reduce the design difficulty of the torsion beam.

[0073] Based on the same inventive concept, the present invention also proposes a vehicle, including a torsion beam, wherein the width, height and thickness of the crossbeam of the torsion beam are determined by the above-mentioned torsion beam optimization design method.

[0074] Based on the same inventive concept, the present invention also proposes a vehicle, including a torsion beam suspension, wherein the torsion beam suspension includes a torsion beam determined by the above-mentioned torsion beam optimization design method.

[0075] Based on the same inventive concept, the present invention also proposes a torsion beam optimization design system, including a computer, wherein the computer stores a computer-usable program code for implementing the above-mentioned torsion beam optimization design method. The computer is used to construct a response surface model based on the change and response relationship between multiple design variables and multiple design indicators of the crossbeam of the torsion beam. Based on the response surface model and multiple design indicators, a genetic algorithm is used to find the optimal solution of multiple design variables. Based on the optimal solution, a torsion beam finite element model is reconstructed, and multiple design indicators of the reconstructed torsion beam finite element model are verified.

[0076] Those skilled in the art will appreciate that the present invention may be implemented in the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may be implemented in the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage and optical storage, etc.) containing computer-usable program codes.

[0077] The present invention is described with reference to the flowcharts and / or block diagrams of the methods and systems according to the embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0078] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0079] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0080] In the description of the present invention, it should be noted that the terms "upper", "lower", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on the present invention. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0081] It should be noted that, in the present invention, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0082] The above description is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features invented herein.

Claims

1. A method for optimizing the design of a torsion beam, characterized in that: The following steps are involved: A response surface model is constructed based on the change and response relationship between multiple design variables and multiple design indicators of the torsion beam; Based on the response surface model and the multiple design indicators, using a genetic algorithm to find the optimal solution of the multiple design variables; Reconstructing a torsion beam finite element model based on the optimal solution, and verifying multiple design indicators of the reconstructed torsion beam finite element model; There are three design variables, including the width, height and plate thickness of the beam; there are six design indicators, including strength, torsional stiffness, shear center height, first-order bending modal frequency, first-order torsional modal frequency and weight; The step of constructing the response surface model comprises: Construct a finite element model of the torsion beam; Conduct DOE orthogonal test analysis on design variables and design indicators to obtain the main effect relationship between design variables and design indicators; Fit the design variables and design indicators and construct the response surface model; The step of performing DOE orthogonal test analysis to obtain the main effect relationship between the design variables and the design indicators includes: sampling the design variables using the full factor method, calculating the design indicators under each group of design variables, and performing DOE orthogonal test analysis on the data to obtain the influence contribution of the design variables on the design indicators; The number of variables for the DOE orthogonal test analysis includes three design variables and six design indicators.

2. The torsion beam optimization design method according to claim 1, characterized in that: After constructing the finite element model of the torsion beam, the method further includes establishing a parameterized variable model using the Morph method to change the width and height of the beam, and changing the plate thickness of the beam by changing the thickness attribute of the beam grid in the finite element model.

3. The torsion beam optimization design method according to claim 1, characterized in that: The step of fitting the design variables and the design indicators comprises: The least squares method, sliding least squares method, Kriging method and radial basis function model are used to fit the three design variables and six design indicators in turn until the mean square error between the calculated fitting results and the simulation results of the finite element model is greater than 0.

95.

4. The torsion beam optimization design method according to claim 1, characterized in that: The steps to verify the strength of the reconstructed torsion beam finite element model include: Based on the reconstructed torsion beam finite element model, a strength simulation condition is established, and the maximum stress value of the reconstructed torsion beam finite element model is simulated and calculated.

5. The torsion beam optimization design method according to claim 1, characterized in that: The steps to verify the torsional stiffness of the reconstructed torsion beam finite element model include: Based on the reconstructed finite element model of the torsion beam, a torsional stiffness simulation is established to obtain the wheel center displacement of the left and right wheels at both ends of the torsion beam. Based on the wheel center displacement and the torsion beam wheelbase, the torsional stiffness is calculated.

6. The torsion beam optimization design method according to claim 1, characterized in that: The steps for verifying the first-order bending modal frequency and the first-order torsional modal frequency of the reconstructed torsion beam finite element model include: The free modal frequency analysis was performed on the reconstructed torsion beam finite element model, and the modal frequencies of each order were calculated. The first-order bending modal frequency and the first-order torsional modal frequency were identified through the modal vibration cloud diagram.

7. A vehicle, characterized in that: It comprises a torsion beam, the width, height and thickness of the crossbeam of the torsion beam are determined by using the torsion beam optimization design method according to any one of claims 1-6.

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